In this paper, numerical simulations of the Navier–Stokes equation
in plane Couette flow configuration have been performed in a range of
Reynolds numbers where the transition to turbulence happens in the form
of oblique bands. Systems with sizes fitting a few elementary cells
\(\lambda _x\times \lambda _z\)  of the pattern have been considered.
These sizes are much larger than the minimal flow unit which allows
the reduction of the transition problem to a temporal process familiar
to chaos theory [1]}. Accordingly, the considered systems
are able to display the first manifestations of a genuinely
spatiotemporal dynamics via patterning. Following the patterns
in time, we showed that they experience orientation and wavelength
fluctuations in the upper part of the range of transitional Reynolds
numbers \([R_{\rm g},R_{\rm t}]\) . A systematic procedure to detect the start and the
termination of well-oriented episodes was defined, leading to the
observation of exponentially decreasing distributions for their
lifetimes (Fig. REF ).
